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nfp: bpf: support arithmetic right shift by constant (BPF_ARSH | BPF_K)

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Code logic is similar with logic right shift except we also need to set
PREV_ALU result properly, the MSB of which is the bit that will be
replicated to fill in all the vacant positions.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jiong Wang 2018-05-18 12:12:10 -07:00 • committed by Daniel Borkmann
parent 991f5b3651
commit f43d0f17fe
2 changed files with 35 additions and 0 deletions
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34
drivers/net/ethernet/netronome/nfp/bpf/jit.c
View file

@ -1916,6 +1916,39 @@ static int shr_reg64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
return 0; return 0;
} }
/* Code logic is the same as __shr_imm64 except ashr requires signedness bit
* told through PREV_ALU result.
*/
static int ashr_imm64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
{
const struct bpf_insn *insn = &meta->insn;
u8 dst = insn->dst_reg * 2;
if (insn->imm < 32) {
emit_shf(nfp_prog, reg_both(dst), reg_a(dst + 1), SHF_OP_NONE,
reg_b(dst), SHF_SC_R_DSHF, insn->imm);
/* Set signedness bit. */
emit_alu(nfp_prog, reg_none(), reg_a(dst + 1), ALU_OP_OR,
reg_imm(0));
emit_shf(nfp_prog, reg_both(dst + 1), reg_none(), SHF_OP_ASHR,
reg_b(dst + 1), SHF_SC_R_SHF, insn->imm);
} else if (insn->imm == 32) {
/* NOTE: this also helps setting signedness bit. */
wrp_reg_mov(nfp_prog, dst, dst + 1);
emit_shf(nfp_prog, reg_both(dst + 1), reg_none(), SHF_OP_ASHR,
reg_b(dst + 1), SHF_SC_R_SHF, 31);
} else if (insn->imm > 32) {
emit_alu(nfp_prog, reg_none(), reg_a(dst + 1), ALU_OP_OR,
reg_imm(0));
emit_shf(nfp_prog, reg_both(dst), reg_none(), SHF_OP_ASHR,
reg_b(dst + 1), SHF_SC_R_SHF, insn->imm - 32);
emit_shf(nfp_prog, reg_both(dst + 1), reg_none(), SHF_OP_ASHR,
reg_b(dst + 1), SHF_SC_R_SHF, 31);
}
return 0;
}
static int mov_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) static int mov_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
{ {
const struct bpf_insn *insn = &meta->insn; const struct bpf_insn *insn = &meta->insn;
@ -2742,6 +2775,7 @@ static const instr_cb_t instr_cb[256] = {
[BPF_ALU64 | BPF_LSH | BPF_K] = shl_imm64, [BPF_ALU64 | BPF_LSH | BPF_K] = shl_imm64,
[BPF_ALU64 | BPF_RSH | BPF_X] = shr_reg64, [BPF_ALU64 | BPF_RSH | BPF_X] = shr_reg64,
[BPF_ALU64 | BPF_RSH | BPF_K] = shr_imm64, [BPF_ALU64 | BPF_RSH | BPF_K] = shr_imm64,
[BPF_ALU64 | BPF_ARSH | BPF_K] = ashr_imm64,
[BPF_ALU | BPF_MOV | BPF_X] = mov_reg, [BPF_ALU | BPF_MOV | BPF_X] = mov_reg,
[BPF_ALU | BPF_MOV | BPF_K] = mov_imm, [BPF_ALU | BPF_MOV | BPF_K] = mov_imm,
[BPF_ALU | BPF_XOR | BPF_X] = xor_reg, [BPF_ALU | BPF_XOR | BPF_X] = xor_reg,

1
drivers/net/ethernet/netronome/nfp/nfp_asm.h
View file

@ -174,6 +174,7 @@ enum shf_op {
SHF_OP_NONE = 0, SHF_OP_NONE = 0,
SHF_OP_AND = 2, SHF_OP_AND = 2,
SHF_OP_OR = 5, SHF_OP_OR = 5,
SHF_OP_ASHR = 6,
}; };
enum shf_sc { enum shf_sc {